This invention relates to devices used to terminate unused cable ports, terminals or the like. The invention is particularly useful for, although not limited to, terminating an unused coaxial cable outlet terminal of the type employed in the cable television industry.
Cable antenna television (CATV) systems are conventionally organized so that a communication signal generated at a central antenna can be received by several individual subscribers who are connected to a single coaxial cable that carries the signal. The system functions by connecting devices, such as directional taps, along the cable, and servicing subscribers with a drop line that is connected to one of the devices. Such devices typically have a plurality of output ports so that service can efficiently be provided to many subscribers in the same geographical area. Each of the output ports is usually a female coaxial plug to which the drop line for an individual subscriber is connected.
In many instances, the number of output ports on one of the devices exceeds the actual number of subscribers that are serviced by that device. In such instances, it is desirable to terminate the unused output ports. Termination of the unused output ports serves two principal functions. First, by terminating such output ports with terminators that have impedances selected to match the impedance of the coaxial cable, there is no impedance mismatch between the signal-carrying cable and the active subscriber cables that are connected. Second, the presence of terminators on the unused output ports acts to prevent theft of the cable signal by nonsubscribers who could otherwise simply attach a coaxial cable themselves to any vacant output port. Alternatively, a terminator may be positioned between a previously used output port and the corresponding drop line when the service to that particular subscriber is suspended; in this instance, service can be restored simply by removal of the interposed terminator without requiring that the full wiring to that subscriber be removed.
It is readily apparent that the second of these functions can only be achieved if the terminator is designed so that it is resistant to attempts by unauthorized individuals to remove it after it has been installed. As a result, in the prior art there have been developed terminators that require the use of a special tool that is not available to the general public in order to remove the terminator. An example of such a terminator is described in U.S. Pat. No. 5,055,060 (Down), U.S. Pat. No. 5,179,877 (Down), and U.S. Pat. No. 5,273,444 (Down). In these patents, the terminator is of the type that includes a connector body that is rotatably encapsulated within a shield. This shield contains two ports: one port receives a cable terminal and the other port is used to provide access to a socket in the connector body. This socket is especially adapted to receive a specialized tool that can be used to rotate the connector body within the shield and thereby fasten the terminator to an output port. In such prior-art devices, however, the design for the interaction between the terminator device and the specialized tool often makes the tool difficult to use.
The effectiveness of such a terminator can be judged by a number of different criteria. Such a device should be designed so that the connection of the impedance-matching resistance to the coaxial cable is reliable; in particular, the coaxial post should be sufficiently durable to avoid being damaged either during shipping or installation, and the device should produce a good ground plane when connected. Moreover, the device should preferably have a sealing member that is configured and dimensioned to provide a secure seal of any components within the connector body. Additionally, it should be possible for the device to be installed and removed easily by an authorized individual and resistant to attempts at removal by an unauthorized person.
The present invention is directed to a tamper-resistant device for terminating a connection. The device comprises a coaxial shell having a first end and a second end; a connector body having a first end and a second end, the connector body being dimensioned and configured to be snap fitted within the coaxial shell and including interior threads disposed at the first end of the connector body adjacent the first end of the coaxial shell; at least one slot in the second end of the connector body for engagement with a cooperating tool to rotate the connector body with respect to the coaxial shell; a resistor case having a first end and a second end, the resistor case mounted within the connector body; and a sealing member between the connector body and the resistor case, the sealing member disposed proximate a portion of the interior threads opposite the first end of the connector body and gripping at least a portion of the first end of the resistor case.
In a preferred embodiment, at least a portion of an outer surface of the second end of the coaxial shell is threaded. Also, the coaxial shell and the connector body are cylindrically symmetric about a longitudinal axis, the inner diameter of the second end of the coaxial shell being substantially equal to the inner diameter of the second end of the connector body. The second end of the connector body preferably includes two slots. Further, the second end of the resistor case includes a cylindrical hole and a frustoconical bevel. The device further comprises a resistor mounted within the resistor case for electrical connection to the coaxial output port. The resistor preferably comprises a central conductor and a body. The impedance of the resistor is preferably about 75 xcexa9.
In the embodiment where the device comprises a resistor with a central conductor and a body, and is mounted with the resistor case for electrical connection to the coaxial output port, there are several preferred features of the device. The central conductor preferably extends through the hole in the resistor case, and is mounted within the resistor case by solder filled in a frustum-shaped cavity defined by the frustoconical bevel. The diameter of the central conductor is preferably between about 0.029 and about 0.035 inches. Most preferably, the diameter of the central conductor is substantially equal to about 0.032 inches. The resistor case is also preferably press fitted to the connector body. Further, the resistor case preferably comprises an annularly shaped ground plane. The outside diameter of the annularly shaped ground plane is preferably greater than 0.280 inches. In one embodiment of the invention, the outside diameter of the annularly shaped ground plane is substantially equal to about 0.281 inches and the inside diameter of the annularly shaped ground plane is substantially equal to about 0.210 inches.
The resistor case may be composed of metal. In a preferred embodiment, the resistor case is composed of brass and is plated with a material selected from the group consisting of nickel and tin. In one embodiment, the connector body is also composed of metal. Where the connector body is composed of metal, it is preferably composed of brass. In another embodiment, the connector body is composed of plastic. Where the connector body is composed of plastic, the connector body is preferably composed of a material selected from the group consisting of Ultem(trademark) and glass-filled polycarbonate. The coaxial shell may also be composed of metal. Where the coaxial shell is composed of metal, it is preferably composed of brass. In a different embodiment, the coaxial shell is composed of plastic. Where the coaxial shell is composed of plastic, it is preferably composed of a material selected from the group consisting of Ultem(trademark) and glass-filled polycarbonate. The sealing member is preferably composed of silicone rubber.
The invention is also directed to a tamper-resistant device for terminating a connection comprising a coaxial shell having a first end and a second end; a connector body having a first end and a second end, the connector body being dimensioned and configured to be snap fitted within the coaxial shell and including interior threads disposed at the first end of the connector body adjacent the first end of the coaxial shell, the connector body further including two slots in its second end for engagement with a cooperating tool to rotate the connector body with respect to the coaxial shell; a resistor case having a first end and a second end, the resistor case being dimensioned and configured to be mounted within the connector body; a resistor mounted within the resistor case for electrical connection to the coaxial output port; and a sealing member between the connector body and the resistor case, the sealing member disposed proximate a portion of the interior threads opposite the first end of the connector body and gripping at least a portion of the first end of the resistor case. In a preferred embodiment, the resistor comprises a central conductor with a diameter between about 0.029 and about 0.035 inches. The central conductor most preferably has a diameter substantially equal to 0.032 inches. The resistor case also comprises an annularly shaped ground plane with an outside diameter greater than 0.280 inches. Preferably, the inside diameter of the annularly shaped ground plane is substantially equal to about 0.210 inches. In one embodiment, the coaxial shell is composed of brass, the connector body is composed of brass, and the resistor case is composed of brass plated with nickel.
The invention is further directed to a tamper-resistant device for terminating a connection comprising a coaxial shell; a connector body having a first end and a second end, the connector body being housed within the coaxial shell and including interior threads, the interior threads disposed at the first end of the connector body; and a resistor mounted within the connector body, the resistor comprising a central conductor and a body, the central conductor having a diameter between about 0.029 and about 0.035 inches. Preferably, the central conductor has a diameter substantially equal to about 0.032 inches.
The invention is additionally directed to a tamper-resistant device for terminating a connection comprising a coaxial shell having a first end and a second end; a connector body having a first end and a second end, the connector body being dimensioned and configured to be snap fitted within the coaxial shell and including interior threads disposed at the first end of the connector body adjacent the first end of the coaxial shell, the connector body further including two slots in its second end for engagement with a cooperating tool to rotate the connector body with respect to the coaxial shell; a resistor case having a first end and a second end, the resistor case being dimensioned and configured to be mounted within the connector body, the resistor case comprising an annularly shaped ground plane with an outside diameter greater than 0.280 inches; a resistor mounted within the resistor case for electrical connection to the coaxial output port, the resistor comprising a central connector and a body, the central conductor having a diameter between about 0.029 and about 0.035 inches; and a sealing member between the connector body and the resistor case, the sealing member disposed proximate a portion of the interior threads opposite the first end of the connector body and gripping at least a portion of the first end of the resist or case. Preferably, the central conductor has a diameter substantially equal to about 0.032 inches. Also, the inside diameter of the annularly shaped ground plane is preferably substantially equal to about 0.210 inches. In one embodiment, the coaxial shell is composed of brass, the connector body is composed of brass, and the resistor case is composed of brass plated with nickel.